Permafrost

Permafrost measurements at Janssonhaugen, Spitsbergen
Photo: Ketil Isaksen MET

An important aspect of climate change in the Arctic is melting of the permafrost. In Svalbard, monitoring of permafrost is ongoing in several boreholes, including at Janssonhaugen, 20km from Longyearbyen. Heating and thawing of permafrost may result in greater instability in hillsides, increasing the probability of landslides and avalanches. Thawing permafrost can damage buildings and infrastructure and cultural heritage sites in coastal areas are exposed to increased erosion.

What is being monitored?

Permafrost

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At suitable places, temperature measurements in boreholes in permafrost give firm indications of changes in climate. Data from Janssonhaugen show a distinct rise in temperature right down to 40 metres. Temperature variations at the ground surface through the year will be both delayed and moderated downwards. At a depth of 15–20 metres, temperature variations through the year are balanced out. Changes in the average temperature at the ground surface over several years and decades will be transmitted to greater depths as temperature waves. These measurements are therefore a valuable supplement to more traditional climate data from meteorological stations in Svalbard.

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The uppermost soil layer in the ground overlying the permafrost thaws each summer. This is called the active layer. The active layer has become thicker since 1998, so that the surface of the permafrost now lies about 25-30 cm deeper than it did around the turn of the century. In the longer term, this thawing can create stability problems at the surface.

Status and trend

Permafrost monitoring began in 1998. Analyses show that the temperature in the upper part of the permafrost is rising on average 0.8°C per decade and that this rise has been accelerating during the past decade.

Rising temperatures in the permafrost have been recorded right down to a depth of 80 metres during the time the monitoring has been taking place. The active layer has become 25–30 cm thicker since 1998.

Causal factors

The warming of the permafrost at Janssonhaugen is first and foremost a response to the rise in the air temperature in recent decades.

Studies so far show that any changes in the snow cover have had no effect on the permafrost at Janssonhaugen. This is because the locality is extremely exposed to wind, and the ground around the borehole is blown free of snow for large parts of the winter.

Consequences

All buildings in the Svalbard settlements are built on piles driven into the permafrost, and roads, bridges, airports and other infrastructure are also constructed on permafrost. When warming and thawing of the permafrost occurs, the infrastructure may be affected in the longer term. In addition, the permafrost is essential for stabilizing steep mountainsides, which may become more unstable when warming takes place. This will have consequences for travelling, and also potentially for animal life if, for example, areas with arctic fox dens become unstable and collapse.

Many cultural heritage remains in Svalbard are situated in the shore zone, where they may be vulnerable to increasing erosion in the future.

On a circumpolar level, the most important consequence of the warming and thawing of the permafrost is, nevertheless, that large volumes of greenhouse gases, like CO2 (carbon dioxide) and CH4 (methane), may be released if ever deeper layers of the permafrost thaw. These gases have been kept out of the atmosphere because the organic carbon has been frozen in the ground. The release of such greenhouse gases may lead to a further rise in the temperature and thawing of the permafrost. This is one of the many feedback mechanisms in the Arctic, and attempts are continually being made to improve the estimates of the emissions from thawing permafrost.

About the monitoring

In cold permafrost, like in Svalbard, there is usually insignificant or no circulation of groundwater to disturb the progress of the temperature in the ground. By observing changes in the temperature at a depth of 30–40 metres over some years, it is possible to calculate the changes in temperature that have taken place near the ground surface over 10–20 years.

It transpires that the active layer, which is the uppermost part of the permafrost that thaws each summer, is becoming thicker over time. This is directly connected with warmer summers and brings with it problems like increased risk of landslides, more erosion on the coast and changes in the landscape. In recent years, international climate researchers have therefore become increasingly interested in the monitoring of permafrost.

Places and areas

Relations to other monitoring

Monitoring programme
International environmental agreements
Voluntary international cooperation
Related monitoring